Mark Tang, a Hongkonger who has been living in Shenzhen for 10 years, has to defer his plan to move back to the city, even though his wife is about to deliver a baby in September.

The businessman, who moved across the border after retiring in his early 40s, bought a 1,670 square foot apartment for 3 million yuan (US$476,940) three years ago, in southern Shenzhen’s Liantang district, an hour’s bus ride from Kowloon Tong in Hong Kong.

“I had no plan to return to Hong Kong until my wife got pregnant. I wanted to educate my child in Hong Kong,” he said. But his plan was cast in doubt after he saw the home prices in Hong Kong, which have placed the city among the least affordable metropolitan areas in the world to live in.

“Now, I could sell the apartment in Shenzhen for about 5 million yuan, which can be used to buy a new apartment of about 300 sq ft in Hong Kong,” said Tang. “Shall I go and downsize in Hong Kong? It would be stupid to act now.”

For the same price, homebuyers can get a new apartment of about 255 sq ft, the equivalent of two car parking spaces, in Henderson Land Development’s South Walk Aura in Aberdeen, which translates to about HK$24,350 per square foot.

“Many of my friends face the same situation as me. Their children have to cross the mainland boundary to attend schools in Hong Kong every day. Some of these kids are already 10 years old and their parents still cannot afford to return to Hong Kong,” he said.

Tang said he would only consider buying a home in Hong Kong if prices dropped. “Nothing will keep rising forever, and not fall,” he said.

The phenomenon of Hongkongers moving to Shenzhen is not new. A total of 61,900 Hongkongers had already lived in the southern Chinese city for three months, according to data released by the Planning Department and the Shenzhen Municipal Statistics Bureau in 2009.

And now, they are deferring plans to move back to Hong Kong, because of the city’s skyrocketing home prices.

Shall I go and downsize in Hong Kong? It would be stupid to act now

Mark Tang, Hongkonger living in Shenzhen

In February, for the first time in Hong Kong, all 50 major housing estates reported that their price per square foot had exceeded HK$10,000. Tin Shui Wai’s Kingswood Villas, only half an hour’s bus ride from Shenzhen, became the latest estate to join the club, according to Ricacorp Properties.

A 448 sq ft apartment in Locwood Court, Phase 1 of Kingswood Villas, sold for HK$5.48 million – or HK$12,232 per square foot – mid last month.

“For the same price, homebuyers can buy an apartment that is much bigger in most places in Shenzhen,” said Andy Lee, the chief executive of southern China at Centaline Property Agency.

With a budget of HK$5.46 million, homebuyers can buy a 949 sq ft apartment in Shenzhen’s Henggang district, which translates to HK$5,753 per square foot, according to Centaline.

The average home prices in Shenzhen were cheaper at HK$6,293 per square foot – or 5,058 yuan per square foot – in 2017, according to data provided by US property services company Cushman and Wakefield, which was about half of Hong Kong’s HK$11,117 per square foot – or 9,834 yuan per square foot.

Hongkongers are, however, subject to some restrictions when it comes to buying homes in mainland cities.

For instance, they need to pay a year’s worth of social security before buying a home and are not allowed to buy more than one home in Shenzhen, according to Midland Realty. Homebuyers from Hong Kong interested in mainland properties also need to keep up with local policy changes and be comfortable with these.

Still, Shenzhen is a more affordable place to live than Hong Kong, in terms of home prices and rental costs, according to Centaline’s Lee, who also said the number of Hongkongers living in Shenzhen now must be much higher than 10 years ago, and that it will increase gradually.